Time delay switch mechanism for camera flash synchronizers



5 1952 M. L. GARDNER 2,620,713

TIME DELAY SWITCH MECHANISM FOR CAMERA FLASH SYNCHRONIZERS Filed'May 19,1950 2 SHEETS-SHEET 1 gags,

Patented Dec. 9, 1952 TIME DELAY SWITCH MECHANISM FOR CAMERA FLASH SYNCHRONIZERS Michael L. Gardner, Berwyn, Ill., assignor to Busch PrecisionCamera Corporation, Chicago, 111., a corporation of Illinois ApplicationMay 19, 1950, Serial No. 162,973

l Claims.

This invention relates to a time delay switch mechanism especially foruse in connection with photographic equipment.

In flash photography a high brilliance light of short duration isproduced by some means such as for example a photo-flash lamp, and whenthe brilliance of the flash is at its approximate peak, the shutter of acamera is uncovered and the sensitive film is exposed. The conventionalmethod of accomplishing these functions employs a battery which isdirectly connected through appropriate switching means to the flash lampand the solenoid operating the shutter. Variations of this scheme arecommon, but all have the same basic disadvantages and problems. Theprincipal disadvantages rest in the necessity of using dry cells, whichrequire constant changing in order to assure positive action. Variationsin current and voltage caused by age, and other conditions,

may prevent correct exposures.

Such disadvantages have given rise to a method of flashing such lampswhich utilizes a capacitor as a storage repository for a charge ofcurrent, and setting off the lamp from the charge remainin on thecapacitor. By means of this method, many of the disadvantages of thedirect connected flashing method have been eliminated.

In the direct connected method, the shutter and its solenoid requiresynchronization in order to assure that the peak of illumination will bereached when the shutter is opened. Many methods of accomplishing thishave been devised, most of which utilize some adjustable lost-motionconnections. These of course are unsatisfactory.

In the battery-capacitor method, a part of the charge of the battery isreleased to the lamp, and the residual charge used to operate theshutter solenoid. The principal object of this invention is to provide adistributing switch mechanism in which the time delay between thepartial discharge of the condenser and the second residuary discharge ofthe condenser accurately can be predetermined.

A further object of the invention is to provide a simple switchingmechanism in which the speed at which the switch is manually operated,or the pressure used by the operator will in no way affect the speed ofmovement of the moving contact of the switch, so that the time delaybetween contact-s will be constant.

Many other objects of the invention lie in the provision of a switchinmechanism having a novel construction and having compactness, re-

2 liability, and simplicity in construction as dependabilit inoperation.

Certain additional objects will appear as the description of my timedelay switch mechanism proceeds, relating not only to the details ofconstruction and arrangement of parts, but as well to novel and improvedcombinations for accomplishing the purposes for which the same isintended. As to those features which are charaotertic of my invention,same have been set forth with particularity in the claims appendedhereto. My invention itself, however, both as to its organization andthe manner of construction, together with additional objects andadvantages thereof, may best be understood by reference to the followingdescription of a preferred embodiment, taken in connection with theaccompanying drawings in which:

Fig. 1 is a front elevational view showing my switch mechanismassociated with a flash gun and camera.

Fig. 2 isa schematic electrical diagram of the circuit in which myswitch mechanism is used.

Fig. 3 is a sectional view taken through my switch mechanism along theline of Fig. l and in the indicated direction.

Fig. 4 is a sectional view taken through the switch and the flash gunalong the line 5-4 of 3 and in the indicated direction.

Figs. 5 and 6 are sectional views taken through the switch mechanismalong the lines 5-5 and 6-6, respectively, of Fig. 4 and in theindicated direction.

Referring now to the drawings, in Fig. 1 there is illustrated thearrangement in connection with which my new switch mechanism is adaptedto be used. The reference character it] designates generally what istermed a flash gun havin the switch mechanism H associated therewith. Atl2 there is shown a camera provided with a shutter (not shown) of anysuitable design in an ap propriate shutter housing [3. A shutteroperating lever It extends out of the housing l3 and is linked to thearmature to of the solenoid It at ll. Many similar arrangements arepossible. The solenoid I8 is electrically connected with the flash gunH! by appropriate electrical leads ensheathed in a cable IS. Theconnectors, plugs, and other constructional details are of no importanceto the invention and hence are not illustrated.

Returning to the dash gun is, same consists of an elongate cannister orhousing IQ, usually cylindrical in formation which is adapted to containthe resistors, condenser, batteries, and conas well nectors necessary torender the same operative. There is a socket 2i mounted upon the upperend of the housing i8 adapted to receive the flash lamp 22 therein. Areflector 23 is mounted in proper relationship to the lamp 22.

With the exception of the switch mechanism, the elements thus farreferred to are conventional and not intended to be considered as a partof this invention in and of themselves. In order to render theunderstanding of the switch mechanism I I complete, an electricaldiagram of the circuit in which sam is used is depicted in Fig. 2 and anexplanation thereof will clarify the manner in which the switchmechanism is utilized.

The switch mechanism H is shown in Fig. 2 in its quiescent or initialposition. The movable arm is free of the lamp contact 3! and thesolenoid contact 32. In operation, it will be moved in acounter-clockwise direction about the pivot 33 and serve to distributethe charge from the condenser 3 3 to the two contacts 3! and 32. Thecondenser 34 has a high capacitance, usually of the order of 1000microfarads and same is connected to ground at 35 through a small safetyresistor 35 in the lead 3'5. The opposite side of the condenser 34 isconnected to the distributing arm 39 by the wire lead 38 and to theresistor 39 which is in series with the battery it. The resistor 39 maybe 100 ohms and the battery a 22 volt B type used in miniature radios.With such values of resistance, capacitance, and voltage, the timeconstant will permit the charging of the condenser 34 in almostnegligible time. The battery is connected to the terminal of the lamp 22through the electrical lead 42. The lamp shell 43 is grounded at dd.

The condenser 84 will charge to its full capacity through the filamentd5 of the lamp 22 immediately that the lamp 22 is inserted in the socket2i, and after the condenser has been charged to its capacity, currentfiow will cease. The rate at which the current will flow during thecharging period is such that the filament c5 of the lamp 22 will notincandesce and hence the lamp 22 will not be flashed. The rate ofcurrent flow is limited by the relatively high resistance 39 in thecircuit.

When it is desired to expose the film, the distributing arm 3! is movedin a counter-clockwise direction in a manner which will be explained,and it engages the contacts 3| and 32 in that order. When the contact 3!is engaged as the arm 39 is passing same, a sudden flow of current iscaused by the partial discharge of the condenser 34. The path of suchfiow is as follows: condenser 36, lead 38, arm 38, contact SI, lead 58,lead d2, lamp terminal 4i, filament 45, lamp shell 43, ground dd, ground35, resistor 36, lead 3!, back to condenser 3d. Since this circuitcontains little or no resistance, the flow of current, although onlymomentary, is suificient to initiate the flashing of the lamp 22. Samemay be filled with aluminum foil, or the like in an atmosphere ofoxygen, so that when the filament 45 incandesces and begins the burningof the foil or other medium, the flash will be self-sustaining, aswell-known in this type of lamp. The peak of brilliance is reached ashort time after the contact 3| has been enga ed.

In the meantime, the distributing arm 38 continues on its path andengages the contact 32. Contact 32 is connected by the lead 5! to thesolenoid coil 52 and thence to ground at 53. Current will thus flowthrough the solenoid coil 52 completing the discharge of the condenser 3The armature [5 will then move to the left, opening the shutter at theproper instant that the brilliance of the flash is at its peak. Theelapsed time between the start of the fiash of the lamp 22 and the timethat the solenoid 56 operates is a direct function of the time requiredfor the arm 3?] to move between the contacts 31 and 32. This time iseasily adjustable as will be described hereinafter, by reason of theconstruction of my new switch mechanism.

It is desired at this time to point out that while the referencecharacters 3i], 3!, and 32 have thus far designated the distributingarm, lamp contact, and solenoid contact, respectively, they are actuallyintended to represent assemblies. The small size of Fig. 2 has made itimpractical to apply more than one reference character to each of theillustrated elements of the switch mechanism 5 l without confusing theillustrations. Hereinafter, the reference characters 3B, 3!, and 32 willall be general assembly designations and will be described as such.

Referring now to Figs. 3 to 6 inclusive, the switch mechanism I! isshown therein on an enlarged scale so that the details thereof morereadily may be explained. The mechanism H is mounted in a hollow housing69' preferably formed of some molded composition such as a phenolicresin, in order that same be non-conducting. At opposite ends thereofare provided recessed slots SI for accommodating th heads of the screws62 by means of which the housing 69 is removably fastened to the side ofthe cannister l9. The upper end of the housing 68 has a centralcylindrical cavity 63 to allow for clearance of the solenoid contactassembly 32. This is connected with an elongate trapezoidal shapedcavity 6 3 having its wider end uppermost as shown in Fig. 4 and whosepurpose is to accommodate the distributing arm assembly 36 and permitits swinging. The connecting cavity E5 in the lowermost part of thehousing 60 accommodates the button and linkage therefor as will bedescribed. The housing Gil has an annular protruding boss 55 having afrusto-conical opening 67 leading to the cavity 65, and the switchbutton 68 xtends out of the opening 67 with its outer end substantiallyfiush with the boss 66 so as to prevent accidental depression thereof. Apart of the housing designated 69 serves as a stop member for limitingthe swinging of the distributing arm assembly 30 in a manner to be eXplained. Obviously, in the event it is desired to make the housing 66from metal, other stop means may be provided or the stop means may beinsulated from the assembly 32.

The contact assemblies and movable parts of the switch mechanism I I areall carried upon an elongate insulating block [8 whose contours are suchas to engage within the conjoined cavities 83, 64, and 65 of the housing60 so that when the housing 56 is assembled upon the gun HI it willcover the said block. The block it is secured to the cannister i9 by thecountersunk head screws H and 12 appropriately screw threaded into theside of the cannister 19. The cannister I9 has five relatively largeopenings provided therein immediately beneath and covered by the block19 whose purpose will resently be clarified. Said openings aredesignated respectively 13, 74, 75, T6, and 86.

At the upper end of the block (as viewed in Fig. 4) there is mounted thesolenoid contact assembly 32. Same consists of a screw threaded stud IIinserted into the block I and having the left hand end thereof providedwith a contact head 18 which protrudes from the bottom of the block 10through the opening 13 and into the cannister 19 where it engages aspring pressed element 19 which connects with lead (see Fig. 2).Obviously, the opening I3 must be of a size sumciently large to clearthe head I8 to prevent electrical engagement between said head I8 andthe cannister I9. The right hand end of the stud 11 extends into thecavity 63 and has a pair of nuts 8| and 82 mounted thereon having a flatlug 83 mounted in sandwiched condition therebetween. The lug 83 ispierced to freely move on the stud I'l somewhat like a washer ifpermitted so to do by the nuts 8| and 82. Obviously, the nuts 8| and 82serve to enable the lug 83 to be adjusted to any position along the studI1 and locked thereat. Likewise, the lug 03 may be secured in any offsetposition desired such as for example as shown in Fig. 3 to permit accessto the head of the screw II for example, or to move the contact point 84in case the part engaging the same has become worn or pitted.

The lamp contact assembly 3I comprises a shaft 05 sliding mounted in apair of ears 88 and 81 and provided with a conical head 88 extendingabove the car 88 as shown in Fig. 4, there being an enlarged diametercollar 89 on the opposite side of the car 86. The shaft is urged in anupward direction as viewed in said Fig. 4 by means of a coiled spring 90wound about the shaft 85 and extending between the inside of the ears.Due to the collar 89 the upward movement is limited, but downwardmovement is possible against the bias of the spring 90. The cars 86 and81 are formed from the sides of a metal standard 9| having an integrallyformed base 92 bent at an angle thereto, overlying the block I0 andengaged thereto by the rivets 93 and 94. The rivet 94 is of conventionaldesign and its lower (left hand) swaged end enters the opening I5 so asnot to establish electrical engagement with the cannister I9, while thesame end of the rivet 93 has a contact head 95 which clears the sides ofthe opening I4 and engages the spring pressed element 99 which connectswith the lead 50 (see Fig. 2).

The distributing arm assembly 30 comprises a pair of elongate taperedarms I00 held in spaced apart condition by the spacer IOI securedbetween the arms intermediate the ends thereof and by the cylindricalspacer-contact bar I 02 secured between the upper ends of the arms I09.The spacer-contact bar I02 serves both as a spacer and contact and henceis formed of a suitable contact metal not readily pitted. It will bereferred to hereinafter as a contact bar since that is its principalfunction. The ends of the arms I00 opposite to those mounting thecontact bar I02 are provided with short pins 33 about whose axis thearms I 00 are adapted to pivot. It will be noted that the arms I00 arespaced apart sumciently to completely clear the contact assembly 3I,except for the conical contact end 88 which will be touched by thecontact bar I02 as the arms I00 swing from the position shown in solidlines in Fig. 4 to the broken line position in said figure.

The pivot pins 33 are mounted at the inner rounded ends of the slots I04formed in the spaced apart uprights I05 of the channel member I06 whosebase I0! is attached to the block I0 by the rivets I08 and I09. Therivet I09 is of conventional construction and its swaged left hand endenters the opening 80, while the rivet I08 is formed in the same manneras the rivet 93, being provided with an enlarged contact head I I0 whichenters the cannister I9 through the opening 16 to electrically engagewith the spring element III. Said element III is connected with the lead38 (see Fig. 2).

The lower end of the button 68 is disposed between the uprights I05 andis of reduced diameter to clear the same, as shown at H3. The button endI I 3 is bifurcated and straddles a toggle link II 4 to which it ispinned at II 5. One end of the toggle link II 4 is pivotally mounted ona pin I I6 which extends between the uprights I05 and the opposite endis secured at II! to a coiled spring II8 which is connected to thecenter of the spacer IOI in the groove I I9. The bifurcated button endH3 is urged to the right as viewed in Fig. 4 by means of a pair ofcoiled springs I20 each mounted on the pin I I6 between the inside ofthe uprights I05 and the end of the toggle link II4, said springs I20each having an end engaged in the base I01 at I2I and another end I22engaging in the bifurcation of the button end II3 under the pivot pinII5. This is best shown in Fig. 4. It will be seen by reference to Fig.3 that the springs I20 also serve to center the toggle link II4 upon thepivot pin II6. The base I01 has an opening I25 to permit access to thescrew 12. For this purpose, the entire distributing arm assembly 30 mayslide out of the slots I04 and with the button 68 and its linkage swingabout the pin II6. Of course the housing 60 must first be removed.

It is of importance that the line between the axis of the spacer IM andthe point ll! be to the right of the axis of the pivot pins 33 as viewedin Fig. 4 when the switch assembly I I is poised for operation. In thiscondition, irrespective of the forces exerted by the springs I20, therewill be a component of force at right angles to the line between theaxis of the pivot pins 33 and the axis of the spacer IIlI tending toswing the arms I00 to the right, or clockwise about the pivot pins 33 asviewed in Fig. 4. Thus the contact bar I02 will remain engaged againstthe stop 69. When the button 68 is depressed against the force ofsprings I20, the link I I4 will swing to the left or counter-clockwiseabout the pivot pin II6 moving the end II! to the left. The spring II8now begins to stretch, but the arms I00 will not move until the linebetween points H1 and axis of spacer I0 I just crosses to the left ofthe pivot axis 33. At this instant, a component of force is created atthe axis of spacer IOI which tends to pull the arms I00 to the left, orcounter-clockwise about the pivots 33. The greater the movement to theleft, the greater proportion of the potential energy in the stretchedspring III} will be acquired by this force. The result is aself-sustaining movement of the arms I00 to the broken line position ofFig. 4 which is at a speed practically independent of the speed at whicha person could press down on the button 60. This can be termed a snapaction. The release of the button 08 will enable the springs I20 toforce the return of the arms I00. Without these springs I20, the armsI00 would remain in the broken line position.

Since, as explained, the delay between the be-- ginning of the flash andthe actuation of the solenoid I6 depends upon the time required betweendistribution of charge to the respective circuits involved, it will beseen that when the bar I02 is against the stop 69 in quiescentcondition, the condenser 34 will charge through the lamp filament 55.When the button 68 is pressed and the bar 162 executes its stroke, thecharge on the condenser at is partially lost to the lamp 222 as the barI02 engages, depresses, and passes the conical contact 88. The currentfiows from the contact 88 to contact 95 in an obvious manner. The barE62 continues its movement and finally comes to rest on the contactpoint 8% where the remainder of the charge is lost to the solenoid l6through the contact 78. The delay between circuit energization ismeasured by the time it takes for the bar I92 to move from contact 88 tocontact point 86, and this time is readily adjustable merely by changingthe position of the lug 83 along the stud ll.

It is desired to point out that while my switch mechanism is mostideally suited for the use in connection with which the specificationhas de scribed the same, namely in flash photography, it is likewisesuitable for use in many fields where two or more consecutive electricalengagements are required to be made with a predetermined delaytherebetween. The invention is likewise not limited by the illustratedarrangement of parts, dimensions, and the like, but is intended to havea breadth commensurate with the scope of the appended claims.

I claim:

1. In a switch of the character described, a bifurcated, pivoted armhaving a spacer bar on the free end thereof, means providing momentaryelectrical contact as the arm passes comprising an elongate memberarranged to enter the bifurcation as the arm moves past the same, havinga rounded tip in path of the bar, adapted to be electrically engaged andpushed aside by said bar as same passes, and spring means opposing themovement of'said tip.

2. In apparatus of the character described, a switch comprising aswingable arm having a pivot and a contact bar on the respective endsthereof, a stop, a snap-action mechanism operably connected with saidarm including a lever pivotally mounted spaced from said pivot andspring means connected between the lever and the arm adapted to move thelever to opposite sides of the pivot and bias said arm against the stop,a pair of spaced apart contacts, and manual means for overcoming thebias and causing the snap-action mechanism to move the arm past thefirst contact and into engagement with the second contact, said firstcontact including a moveable member disposed between said pivot and barand having a retractile tip mounted in the path of said bar electricallyengaging therewith as said arm is passing.

3. A switch mechanism for flash camera apparatus having a flash lampcircuit, a shutter solenoid circuit, a condenser charging circuit and acharged condenser for energizing both the lamp and shutter solenoidcircuits, comprising a pair of spaced apart contacts respectivelyconnected to the lamp and solenoid circuits, an elongate pivotal memberhaving a charge distributing contact bar on the upper end thereof, andmeans for pivoting said member at a uniform rate of speed 8 whereby tocause said bar to engage the lamp and solenoid contacts consecutivelyfor distributing a portion of the charge from said condenser to saidlamp and solenoid circuits, the first of said contacts being retractileso as to permit the bar to pass same after engagement therewith toengage the second contact, said member having its pivot at the oppositeend thereof, said means including a pivotally mounted lever spaced fromthe pivot, a spring member having one end thereof connected to thecenter of the said member and its other end connected to said lever,said spring biasing said member in a direction away from the contacts,and a manually operable push rod adapted to engage said lever for movingthe member past said pivot and spring means connected to the lever forreturning said member to the opposite side of the pivot.

4. A switch mechanism for fiash camera apparatus having a flash lampcircuit, a shutter solenoid circuit, a condenser charging circuit and acharged condenser for energizing both the lamp and shutter solenoidcircuits, comprising a pair of spaced apart contacts respectivelyconnected to the lamp and solenoid circuits, an elongate pivotal memberhaving a charge distributing contact bar on the upper end thereof, andmeans for pivoting said member at a uniform rate of speed whereby tocause said bar to engage the lam and solenoid contacts consecutively fordistributing a portion of the charge from said condenser to said lampand solenoid circuits, the first of said contacts being retractile so asto permit the bar to pass same after engagement therewith to engage thesecond contact, said member having its pivot at the opposite endthereof, said means including a pivotally mounted lever spaced from thepivot, a spring member having one end thereof connected to the center ofthe said member and its other end connected to said lever, said springbiasing said member in a direction away from the contacts, and amanually operable push rod adapted to engage said lever for moving thememher past said pivot and sprin means connected to the lever forreturning said member to the opposite side of the pivot, said membercomprising a pair of spaced apart arms having said contact bar connectedbetween the upper ends of the arms and having a spacer memberintermediate the ends of the arms to which said one end of the springmember is secured.

MICHAEL L. GARDNER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number

